If you are saving elements as GDL objects, you will have no control over how the script is generated.
You just have to try to understand it and edit it.
If you want complete control, then you have to create the scripts yourself.
Create the elements (prisms, etc.), move and rotate them, create for/next loops, gosub routines, add hotspots etc.
As to how to create a complex model in GDL, that would be almost impossible to say.
You will just have to make a start and ask questions as you get stuck.
To script something like that crane, you would want to have a pretty decent knowledge of GDL, especially if you want to make it parametric (stretchy and moveable).
It is not something I would want to attempt.
Versions 6.5 to 22
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision M6800 - i7 4700MQ @ 2.40GHz, 16GB RAM, AMD FirePro M6100 (2GB), Windows 7 64bit